Gas lift valves



N. F; BROWN GAS LIFT VALVES April 2, 1968 2 Sheets-Sheet 1 Filed Dec. 8, 1964 Fig.2

, INVENT'OR Norman E Brown April 1953- I N. F. BROWN 3,375,847

GAS LIFT VALVES Filed Dec. 8, 1964 2 Sheets-Sheet 2 #2 9a. rm

- INVENTOR Norman F. Brown i United States Patent 3,375,847 GAS LIFT VALVES Norman F. Brown, Dallas, Tex., assignor to Otis Engineering Corporation, Dallas, Tex., a corporation of Delaware Filed Dec. 8, 1964, Ser. No. 416,695 15 Claims. (Cl. 137155) ABSTRACT OF THE DISCLOSURE A flexible flow control valve, or gas lift valve, which may be passed through flow conductors having relatively sharp bends formed therein, and having a flexible pressure chamber provided therein for controlling opening and closing of the valve.

This invention relates to gas lift valves for use in re moving fluids from the bores of Wells by gas pressure.

It is an object of this invention to provide a new and improved tool for admitting fluids into a tubing disposed in a well bore.

It is also an object of this invention to provide a new and improved gas lift valve.

It is an object of this invention to provide a gas lift valve which may be passed through tubing strings having bends which prevent movement of conventional substantially rigid gas lift valves.

It is another object of this invention to provide a new and improved well tool for removing the liquids produced by wells through an inner well tubing disposed in a casing of a well wherein gas from the annular flow passage between the We] casing and the inner well tubing provides the lifting power for removing the liquids to the surface through the inner well tubing.

It is a further object of the invention to provide a well tool for automatically removing liquid from the bore of a well which includes a valve which opens intermittently to permit flow of gas from the annular flow passage between the well casing and an inner well tubing into the well tubing to transport liquids present in the well tubing above the valve to the surface.

It is an additional object of the invention to provide a gas lift valve of the concentric type wherein the valve elements are concentric with the well casing and with a central flow passage passing through the gas lift valve.

It is another object of the invention to provide a valve structure in a gas lift type valve which includes a resilient tubular valve element which surrounds a flow passage extending through the gas lift valve and is radially contractible and expansible for controlling lift gas admission ports into the gas lift valve.

It is another object of the invention to provide a gas lift type valve having concentric valve structure and valve control means including a sealed gas filled reservoir which is charged to a predetermined operating pressure.

It is another most important object of the invention to provide a gas lift valve having a dome or pressure chamber which is flexible to facilitate movement of the valve through curved tubing.

It is an additional important object of the invention to provide a flexible gas lift valve having a flexible dome providing a maximum size pressure chamber occupying a minimum length of the gas lift valve.

It is a still further object of the invention to provide a gas lift valve having a flexible dome formed in the shape of a helically wound elongated tube.

It is a still further object of the invention to provide a flexible gas lift valve of the concentric type having a flexible, helically wound dome enclosed in a resilient sleeve above the concentric valve element and a flexible 3,375,847 Patented Apr. 2, 1968 joint below the concentric valve element to facilitate passage of the gas lift valve through tubing having bends therein.

It is another object of the invention to provide a concentric type gas lift valve which provides a maximum size flow passage for well fluids and a maximum volume dome gas chamber to permit valve operation with a minimum change in dome gas pressure.

It is an additional object of the invention to provide a cencentric type gas lift valve having an annular resilient check valve to prevent flow of well fluids from within the valve into the annular space between the tubing and the Well casing.

Additional objects and advantages of the invention will be readily apparent from the reading of the following description of a device constructed in accordance with the invention, and reference to the accompanying drawings thereof, wherein:

FIGURE 1 is a schematic representation partially in section and partially in elevation illustrating a gas lift valve constructed in accordance with the invention positioned within well tubing in a well located at the bottom of the body of water and having tubing and service lines extending thereto from an operating location on shore;

FIGURE 2 is a longitudinal view partially in elevation and partially in section of a locking tool used to suspend the gas lift valve of FIGURE 1 in the well tubing;

FIGURES 3, 3-A, and 3-B taken together constitute a view partially in section and partially in elevation of a gas lift valve constructed in accordance with the invention; and

FIGURE 4 is an enlarged fragmentary view in section along the line 4--4 of FIGURE 3-A.

Referring now to FIGURE 1, an offshore well is drilled from the bottom 11 of the body of Water 12 to the desired depth and cased with a casing string 13 which may extend from the bottom to a producing zone. An underwater Well head 14 is secured on the upper end of the casing to permit tubing and service lines to be connected into the well. A tubing string 15 and a gas conduit extend from an onshore location to the Well head. At the top of the casing both the tubing 15 and the conduit 20 each contain a rather short radius bend. The tubing 15 contains an enlarged portion 21 comprising the curved or bend portion of the tubing string. The pumps 22 and 23 are provided in the tubing string and gas conduit, respectively, so that desired fluid pressures may be built up in these lines from the onshore location. The tubing string extends downwardly through the casing to a level above a producing zone where a conventional form of packer 24 is set within the casing to seal ofi' the annular space between the casing and the tubing. A landing nipple 25 is made up in the tubing string at a location to position the nipple at, a level within the well to support the gas lift valve below the elevation to which the well fluids will rise within the tubing string. The landing nipple supports a locking tool from which is suspended a gas lift valve 31 constructed in accordance with the invention. The tubing string is provided with lateral ports 32 to permit entry of gas into the string around the gas lift valve from the annular space 33 between the casing and the tubing string. The flexibility of the gas lift valve readily permits its passage through the curved portion 21 of the tubing string.

As illustrated in FIGURE 2, the landing nipple 25 is connected into the tubing string 15 by couplings 3 4 and 35; The details of the locking tool 30 are illustrated in FIGURE 2. The locking tool is of the types illustrated and described in US. Patent No. 2,798,559, issued to I. V. Fredd, July 9, 1957, and US. Patent No. 3,040,808, issued to Harry B. Schramm, June 26, 1962.

Referring to FIGURE 2, the locking tool includes a main mandrel which is provided with a longitudinal bore 41. The mandrel supports a pair of selector keys 42 and 43 which are biased outwardly from the mandrel by the springs 44. When the locking tool is fully engaged Within the landing nipple the selector keys are biased outwardly by the springs into the complementary shaped annular key grooves 45 and formed within the landing nipple. In this position the engagement of the downwardly facing selector key shoulders 51 with the upwardly facing landing nipple shoulder 52 prevents downward movement of the locking tool through the landing nipple. The upwardly and inwardly sloping surfaces 53 and 54 on the selector keys and the surfaces 55 and 60, respectively, within the landing nipple permit upward movement of the locking tool. As explained in more detail in the Fredd Patent No. 2,798,559, the selector keys perform a locating function in that the locking tool is moved through the tubing string until it arrives at a landing nipple having key grooves corresponding to the configuration of the selector keys. The locking tool is locked in the landing nipple against upward movement by the locking dogs 61 which engage the internal annular locking groove 62 formed within the landing nipple. The locking dogs are moved outwardly into the locking groove and held therein by downward movement of the locking sleeve 63 which slides on the upper mandrel 64. The locking sleeve is provided with an undercut fishing neck 65. The dog holder is threadedly engaged on the upper mandrel to retain the dogs around the mandrel. A packing assembly 71 is carried by the main mandrel for sealing the annular space between the locking tool and the landing nipple to prevent fluid flow therebetween. The lower portion of the main mandrel is provided with threads 72 for connecting the gas lift valve to the locking tool.

A gas lift valve constructed in accordance with the invention is illustrated in detail in FIGURES 3, 3A and 3-B. The gas lift valve includes a head member 80, a flexible dome section 81, a concentric valve section 82 and a bottom sub 83 which is connected to the valve section by a flexible sleeve 84. The provision of the flexible dome section and the flexible sleeve connecting the bottom sub to the remainder of the lift valve provides a segmented or articulated form of valve structure wherein the various functions of the valve are performed by apparatus in different sections of the valve which are interconnected by flexible couplings so that no portion of the valve apparatus is so long that the valve may not pass through a curved tubing section having a rather small radius.

The head is provided with an internally threaded bore 85 to permit the connection of the locking tool 30 and with a smaller longitudinal bore 90. A lateral opening 91 extends into the side of the head and interconnects with a longitudinal flow passage 92 which extends downwardly and opens out through an enlarged portion 93 through the lower end of the head. The lateral opening 91 is closed by a plug 94 which may be loosened to allow gas to be injected into the opening. Secured in the enlarged flow passage 93 is a fitting 95 to which a helical or spiral tube is suitably secured, such as by welding. The tube 100 functions as the dome or gas storage chamber of the gas lift valve. The dome is preferably a metal tube of substantial length which has been formed in the shape of a spiral to provide a concentric chamber of substantial volume having lateral flexibility. In addition to the tube being a gas chamber, the coils of the tube define a tubular member through which the well fluids flow through the dome section of the valve. A mandrel 101 is connected to the lower end of the dome. The mandrel is provided with a longitudinal passage 102 which opens into a larger longitudinal passage 103 extending through the upper end of the mandrel and in which is engaged a tube fitting 104 into which the lower end of the dome 100 is suitably connected to provide fluid communication between the dome and passageways 102 and 103. A resilient tubular sleeve 105 is fitted over the dome and secured at the upper end to the head 80 and at the lower end to the mandrel 101. The sleeve preferably is a woven wire structure having an inner and outer coating of rubber-like material. The sleeve covered dome forms a flexible portion comprising a substantial length of the gas lift valve. The upper end of the sleeve 105 is secured on the lower end of the head by the retainer which is constructed of a deformable material, such as a soft metal, provided with ridges 111 which force the inner surface of the sleeve 105 into sealed relationship around the teeth 112 on the lower end of the head to tightly secure the sleeve on the head and effect a seal between the sleeve and the head. The lower end of the sleeve 105 is similarly secured on the upper end of the mandrel 101 by a retainer 113 having ridges 114 which press the inner surface of the sleeve 105 into the teeth 115 on the upper end of the mandrel to secure the sleeve 105 and establish a seal between the mandrel and the inner surface of the sleeve.

Referring to FIGURES 3 and 3-A, the mandrel 101 is provided near its upper end with a downwardly facing shoulder 121 and an external annular seal ring groove 122. Below the seal ring groove the mandrel is slightly reduced in diameter along a section 123 and provided with a plurality of serrations or annular ridges 124 to aid in holding the concentric valve member as will be later explained. The mandrel is further reduced in diameter along the portion 125 which extends from the section 123 of the mandrel to an external annular flange defining the section of the mandrel around which a concentric valve member is positioned. At the lower end of the section 125 the outer surface of the mandrel is provided with a plurality of ridges or serrations 131 to aid in gripping the lower end of the concentric valve member around the mandrel. Another external flange 132 is formed around the mandrel below and spaced apart from the flange 130. The flange 132 defines a downwardly facing shoulder 133. Below the shoulder 133 a section 134 of the mandrel has a diameter the same as the diameter of the mandrel above the flange 130 and is provided along a portion of its length near the shoulder 133 with a plurality of ridges or serrations 135 to aid in gripping a check valve as will be later explained. Beginning at the lower end of the section 134 the mandrel is slightly enlarged in the diameter forming the downwardly and outwardly facing shoulder 140. Immediately below the shoulder a plurality of upwardly and inwardly directed ports 141 extend through the mandrel. External ring grooves 142 and 143 are formed in the mandrel below the ports. Below the groove 143 is an annular locking ring groove 144. The mandrel is provided with a plurality of external teeth 145 below the locking ring groove 144, and the lower end of the mandrel has a downwardly and inwardly sloping external surface 150.

A sleeve 151 is secured around the mandrel extending from the shoulder 121 at the upper end of the mandrel to the locking ring groove 144 near the lower end of the mandrel. Upward movement of the sleeve is limited by the contact between the upper end of the sleeve and the shoulder 121. A seal ring 152 is fitted in the groove 122 to form a seal between the mandrel and the upper inner surface of the sleeve. A plurality of horizontal slots 153 are provided through the sleeve to allow the passage of lift gas, as will be explained. The sleeve is reduced in internal diameter along a portion 154 which is broached to form a plurality of longitudinal grooves 155, as may be seen also in FIGURE 4. The lower end of the portion 154 of the sleeve is tapered downwardly toward the inner surface of the sleeve at to form a seat for the check valve, as will be explained. A bushing 161 is suitably secured, such as by welding, into the lower end of the sleeve 151. The seal rings 162 and 163 are fitted in the grooves 142 and 143, respectively, to form a seal between the inner surface of the bushing and the mandrel below the ports 141 to prevent flow of lift gas along the surface between the bushing and the mandrel. A lock ring 164 is engaged in the groove 144 against the lower end of the bushing to secure the sleeve 151 against downward movement.

The concentric valve element 165 is positioned around the section 125 of the mandrel confined between the external surface of the mandrel and the internal surface of the sleeve 151. The valve is a molded tubular member formed of a resilient rubber-like material. The central portion of the concentric valve has suflicient flexibility that it may move laterally within the annular space 170 between the sleeve and the mandrel to open and close the slots 153 through the sleeve. The upper end of the concentric valve is confined along the portion 123 of the mandrel between the mandrel and the inner surface of the sleeve with the ridges 124 aiding in firmly securing the valve around the mandrel. The lower end of the concentric valve is secured around the lower portion of the section 125 of the mandrel over the ridges 131 by a retainer 171. The retainer 171 is constructed of a deformable material, such as a soft metal, which may be fitted around the mandrel over the lower end of the concentric valve and pressed into contact with the outer surface of the mandrel with the retainer deforming around the flanges 130 and 132 and closely fitting around and firmly securing the lower end of the valve around the mandrel. The retainer 171 also performs a similar securing function in holding the check valve in position, as explained hereinafter.

An annular check valve 1'72 is secured around the mandrel along the portion 134 with the upper end of the check valve being in engagement with the shoulder 133 on the mandrel. The check valve is a tubular member formed of a resilient, rubber-like material, such as the concentric valve, so that lateral movement of the check valve may occur between the mandrel and the sleeve 151. The lower portion of the retainer 171 fits around the upper portion of the check valve below the flange 132 to secure the check valve to the mandrel with the upper portion of the check valve being confined within the retainer and pressed against the ridges 135 to securely maintain the check valve in place. The lower end of the check valve is sufliciently resilient that it may readily move laterally between the external surface of the mandrel and the internal surface of the sleeve 151 below the lower end of the portion 154 of the sleeve. When the check valve is fully folded inwardly around the mandrel its lower end will rest adjacent the shoulder 140 on the mandrel. When the checlt valve is flared outwardly to its fullest extent the outer surface of its lower end will rest against the portion 160 of the broached section of the sleeve 151 thereby closing olf the slots 155 through the Sleeve to prevent fluid flow upwardly from below the check valve. As will be more thoroughly explained hereinafter, the concentric valve 165 moves laterally to open and close the ports 153. Lift gas enters the ports 153 when the valve is open flowing downwardly through the annular space 170, through the longitudinal grooves 155, past the check valve which is displaced inwardly around the mandrel by the gas flow and into the annular space 173 around the mandrel within the sleeve 151 along the ports 141. The lift gas enters the ports 141 from the annular space 173 to flow into the longitudinal flow passage 174 through the mandrel. Backfiow of gas from the annular space 173 toward the ports 153 is prevented by the check valve which flares outwardly when gas flow occurs below it forcing the resilient valve element to contact the inner surface of the sleeve 151 along the portion 160 effectively preventing the backflow of the well fluids or lift gas from the gas lift valve.

The concentric valve portion and the lower sub 83 are connected by the resilient sleeve 84, as shown in FIGURE 3-A, which is fitted at its upper end around the lower portion of the mandrel confined by an annular retainer 175 constructed of a deformable material, such as a soft metal. The retainer is pressed inwardly around the sleeve to force the inner surface of the sleeve into contact with the teeth 145 on the lower end of the mandrel confining the sleeve within the retainer around the mandrel and firmly securing the sleeve to the mandrel. The upper end 6 of the sub 83 is provided with a tapered surface below which are a plurality of teeth 13.1 around which the lower end of the sleeve 84 is secured by the annular retainer member 182 which, like the member 175, is a deformable material, such as a soft metal. The retainer is pressed around the sleeve to force the inner surface of the lower portion of the sleeve into intimate contact with the teeth 181. The lower sub is also provided with an upwardly facing shoulder 182., as shown in FIGURE 3-H, and an annular locking ring recess 183, as shown in FIGURE 3-A. A seal assembly 184 is fitted around the lower sub confined between the shoulder 182 and a retainer ring 185 which is secured against upward movement by the locking ring fitted in the groove 183. The seal assembly 184 provides a lower seal around the gas lift valve between the lower sub and the inner surface of the tubing string 15 in which the valve is positioned in operation. The lower sub is provided with a longitudinal bore 191 providing a flow passage therethrough.

The installation and operation of the gas lift valve is carried out in the following manner. Prior to securing the gas lift valve to the equipment to be used in installing it in a well the dome 180 is charged with a compressible gas to a pressure determined by the lift gas pressure at which it is desired that the valve open. The plug 94 is the lateral opening 91 is loosened so that the compressible gas may be injected into the dome through the opening. The gas passes through the passageway 92 and the fitting 95 into the spiral shaped dorne 100. From the lower end of the dome the gas flows through the fitting 164 into the passageway 102 in the upper portion of the mandrel. From the passageway 102 the gas passes into the annular space 176 behind the concentric valve 165. The space from the plug, 94 through the dome into and including the annular space behind the concentric valve is filled with the injected gas until the pressure of the gas is at the desired predetermined value. The pressure of the dome gas behind the concentric valve biases the valve toward the inner wall of the sleeve 151 over the ports 153 through the sleeve. So long as the pressure around the gas lift valve as exerted against thexconcentric valve through the ports is less than the pressure within the dome behind the concentric valve, the valve will remain in sealing relationship over the ports to close the ports off. When the dome has been sufiiciently charged the gas is sealed in the dome by the plug 94. The dome 100 is sufficiently long to provide adequate volume to cause the concentric valve to open and close with no appreciable change in dome gas pressure thus minimizing the spread between the opening and closing of the valve.

After the compressible gas has been sealed in the dome, as above described, the gas lift valve is secured on the lower end of the locking tool 30 by threadedly engaging the lower end of the locking tool with the threads 85 in the head 80 of the valve. The upper end of the locking tool is then secured to a suitable running tool for inserting the gas lift valve into the tubing string of a well. Since the gas lift valve is particularly suited for and will be used in a well such as illustrated in FIGURE 1 which has tubing having curvatures with the relatively short radii, the running tool must be sufliciently flexible to perrnit it to pass through a curved tubing string. A suitable flexible running tool is fully described in US. Patent No. 3,040,808 issued to Harry B. Schrarnm, June 26, 1962. With the gas lift valve engaged on the locking tool and the locking too'l connected to the running tool, the valve is inserted into the tubing 15 and pumped through the tubing until it is at the desired level in the tubing within the well casing 13. The curved section 7.1 of the tubing string, which may have a radius of approximately five feet, is readily traversed by the flexible gas lift valve and the running tool. The flexible dome section of the gas lift valve and the flexible lower connection between the mandrel and the bottom sub of the valve provide the necessary flexibility in the gas lift valve itself to allow it to pass through the curved portions of the tubing string. By making the gas lift valve in the previously described segments, each of the segments may be short enough to pass through curved tubing while the elongated dome portion of the valve is itself flexible due to the spiral configuration of the tubing comprising the dome together with the flexible housing around the dome.

The gas lift valve is lowered into the well to an elevation such that the well fluids will rise within the tubing string to a level above the valve which will allow the lift gas injected into the tubing string through the valve to lift the well fluids to the surface. The exact elevation at which the gas lift valve is to be located is predetermined and the landing nipple is positioned within the tubing 15 at a level which will place the locking too-l and consequently the gas lift valve at the desired elevation. The landing nipple is provided with the key grooves and which correspond to the configuration of the keys 42 on the locking tool and thus when the locking tool arrives at the landing nipple the selector keys which are spring biased outwardly will engage the key grooves to prevent further downward movement of the locking tool. The inward movement of the selector keys permits them to pass obstructions which may be encountered in inserting the gas lift valve and locking tool into and through the tubing string. The selectibility feature provided the locking tool by the selector keys permits it to be passed downwardly through the tubing string until it arrives at a landing nipple which has key grooves corresponding with the external configuration of the selector keys. Once the locking tool is properly positioned, it is locked in place by expansion of the locking dogs 61 on the upper end of the locking tool. The dogs are expanded by effecting downward movement of the sleeve 63 by the running tool.

When the locking tool and gas lift valve are properly positioned within the tubing string in the well, as above described, the running tool is disengaged and withdrawn from the tubing string. The gas lift valve is thus supported within the tubing string by the locking tool 30. The upper packing assembly 71 on the locking tool forms a seal between the tool and the inner surface of the landing nipple while the seal assembly 184 on the lower end of the gas lift valve also forms a seal with the inner surface of the tubing string, the two seal assemblies cooperating to provide an annular space around the lift valve and locking tool which is in communication through the ports 32 in the tubing string with the annular space 33 around the tubing string within the well casing 13. The annular space 33 is, of course, closed off at its lower end by the packer 24. Lift gas is injected through the conduit 20 into the annular space 33 from which the lift gas flows into the tubing string around the gas lift valve through the ports 32. The lift gas flows into the gas lift valve through i the ports 153. So long as the pressure of the lift gas is below a predetermined valve, the gas within the dome acting through the passageway 102 behind the concentric valve 165 maintains the valve in sealing relationship over the ports 153 to prevent the lift gas from entering the gas lift valve.

When the pressure of the lift gas exceeds the pressure of the gas within the dome, the lift gas will exert sufficient force against the outside surface of the concentric valve to press the valve inwardly in the annular space 170 to uncover the ports 153 allowing the lift gas to pass through the ports into the annular space. The lift gas flows through the ports into the annular space 170 around the concentric valve and downwardly through the slots in the sleeve 151 past the check valve 172 which the gas urges inwardly. When the lift gas passes the lower end of the check valve it flows into the annular space 173 and through the ports 141 into the internal longitudinal flow passage 174 of the mandrel. Since the various parts of the gas lift valve and the locking tool are provided with longitudinal bores forming a continuous, unobstructed flow passage through both the gas lift valve and the locking tool, well fluids readily rise within the tubing string into the gas lift valve and through the gas lift valve above the ports 141. The lift gas entering through the ports 141 aerates the column of well fluids and thus aids in flowing the well fluids to the surface. So long as the pressure of the lift gas within the annulus 33 acting through the ports 32 and the ports 153 exceeds the pressure of the gas in the dome 100, the concentric valve will remain open allowing the lift gas into the tubing string to raise the well fluids to the surface.

Since the pressure responsive elements of the dome are not exposed to the flow passages through the gas lift valve in which the well fluids are located, the concentric valve operation is determined solely by the pressures of the dome gas and the lift gas and is not affected by the pressure of the well fluids within the tubing string. When the pressure of the lift gas drops below the pressure of the dome gas, the dome gas behind the concentric valve forces the concentric valve into sealing relationship over the ports 153 to close the ports and prevent further flow of lift gas into the gas lift valve. Any tendency of the fluids within the tubing string to back-flow through the gas lift valves toward the annular space 33 around the tubing string is prevented by the check valve 172 around the mandrel. The well fluids flow through the ports 141 into the annular space 173 around the mandrel within the sleeve 151. The fluids will then flow upwardly beneath the check valve causing the lower end of the valve to be moved or flared outwardly until the lower end of the valve engages the internal surface of the sleeve 151 along and below the surfaces to effect a seal which prevents flow of the well fluids into the longitudinal slots 155, thus effectively performing a check valve function in the gas lift valve.

The gas lift valve may be removed from the tubing string by the running tool which is inserted into the tubing string and pumped downwardly therethrough until it automatically latches on to the upper end of the locking tool 30. The locking dogs 61 on the locking tool are retracted. Reversal of the pumping fluid firstly retracts the locking dogs 61 and then continued upward force on the locking tool due to surfaces 55 and 60 causes the selector keys to move inwardly and the tool and gas lift valve are withdrawn from the tubing string. The flexible dome portion and the flexible lower section of the gas lift valve readily permits it to be withdrawn through sections of the tubing string having bends of short radius.

If more than the single gas lift valve illustrated in FIG- URE 1 are desired in a tubing string, the number of landing nipples equal to the number of valves to be used are positioned at the desired elevations in the tubing string so that each of the gas lift valves and its associated locking tool may be introduced into the tubing string and properly positioned. The use of locking tools having selector keys readily facilitates selective positioning of several such tools within a tubing string. Each of the landing nipples is provided with key grooves such as the grooves 45 and 50 illustrated in FIGURE 2 to correspond with the selector keys on each of the locking tools. The nipple having the largest set of key grooves is located at the lowest level within the well and progressively coming up the well each of the landing nipples have smaller key grooves. When the first of the locking tools is inserted with the largest of the selector keys the tool will pass all of the key grooves in the various locking mandrels until it arrives at the lowermost which has key grooves sufficiently large to accept the selector keys. By this means a plurality of locking mandrels supporting gas lift valves may be placed in a single tubing string one above the other.

While an enlarged section 21 is illustrated in the tubing in FIGURE 1 it is to be understood that such enlargement is not essential to insertion of the gas lift valve but is employed to facilitate insertion of the particular running tool suggested. With a running tool of equal flexibility to the gas lift valve no enlargement of the tubing at the bends is necessary. Also, the bend illustrated in conduit 20 is not required since no tools, only fluids, are injected through such line.

Other suitable locking devices may be used for the purpose of supporting the gas lift valve within the tubing string. For example, a locking device similar to that disclosed herein shown in US. Patent No. 2,798,559, issued to J. V. Fredd, July 9, 1957, may be used for this purpose.

The concentric valve section of the gas lift valve may be modified to some degree. For example, structure of a concentric type valve which may be employed is illustrated at pp. 3720-3721, of the Composite Catalogue of Oil Field Equipment and Services, 1964-65 Edition, published by World Oil, Houston, Tex.

It will now be evident that there has been described and illustrated a gas lift valve which may be inserted into and removed from a tubing string having bends therein of such a curvature to prevent the passage therethrough of a conventional, substantiallyrigid, gas lift valve.

It will further be evident that the gas lift valve includes both a flexible section and a flexible interconnection between relatively short rigid sections to provide an articulated structure which may readily be passed through a tubing string which has bends of fairly short radius.

It will also be seen that there has been provided a gas lift valve for removing liquids from wells through an inner well tubing disposed in a casing of a well wherein gas from the annular flow passage between the well casing and the inner well tubing provides the lifting power for removing the liquids to the surface through the tubing.

It will additionally be seen that there has been provided a well tool for automatically removing liquids from the bore of a well including a valve which opens intermittently to permit gas to flow from an annular flow passage between the well casing and an inner well tubing into the well tubing to transport the liquids present in the well tubing above the valve to the surface.

It will additionally be seen that the gas lift valve is of the concentric type wherein the valve elements themselves are concentric with the well casing and with a fluid flow passage extending through the gas lift valve.

It will also be evident that there has been provided a gas lift type valve having concentric valve structure and valve control means which includes a sealed, gas filled reservoir which is charged prior to installation to predetermined operating pressure.

It will be further seen that the gas lift valve has a dome structure for operation of a concentric valve which structure is per se flexible and is covered with an impervious flexible housing.

It will in addition be seen that there has been provided a concentric type gas lift valve having dome structure comprising a helically wound tube which will flex laterally and which has sufiicient volume to permit actuation of a concentric valve without appreciable pressure change.

It will be further evident that the gas lift valve has a concentric valve for admission of lift gas which valve is operable by the pressure of the lift gas independent of the pressure of the well fluids in the central flow passage through the valve.

It will also be evident that the gas lift valve includes an annularresilient safety valve to prevent back flow of well fluids from the tubing string into the annular space around the tubing string within the well casing.

The foregoing description of the invention is explanatory only, and changes in the details of the construction illustrated may be made by those skilled in the art, Within the scope of the appended claims, without departing from the spirit of the invention.

What is claimed and desired to be secured by Letters Patent is:

1. A well tool for admitting fluids into the interior of a tubing comprising in combination: body means having a longitudinal flow channel extending therethrough; said body being provided with a first set of ports communicating with the exterior of said body means and a second set of ports spaced apart from said first set of ports communicating with the central flow passage through said body means; said body means being further provided with an annular space concentric with said central flow passage for conducting fluids from said first set of ports to said second set of ports; an annular resilient valve element secured within said annular space to control fluid flow through said first set of ports; said body means being further provided with laterally flexible means forming a sealed chamber disposed annularly about said longitudinal flow channel through said body and in communication with said valve element for containing a gas behind said valve element opposite said first set of ports whereby said valve element is biased toward said ports by said gas; said laterally flexible means providing for significant lateral bending to permit said body means to pass through a tubing having a short radius bend therein.

2. A well tool for admitting fluids into the interior of a tubing comprising in combination: articulated body means having a central fluid flow passage extending theretbrough; a first section of said body means being provided with first ports for admitting fluid into said body means and with second ports for admitting fluid into said central flow passage, said section being further provided with an annular space providing fluid flow between said first ports and said second ports; a resilient concentric valve element positioned within said annular space for controlling fluid flow through said first ports; and laterally bendable means providing a gas chamber in a second of said sections, said chamber being disposed substantially annularly surrounding said central flow passage and interconnected with the annular space in said first section behind said valve element whereby a charge of gas in said chamber will exert a pressure behind said valve element biasing said element toward said inlet ports; said laterally bendable means providing for lateral flexing of said body of said gas lift valve permitting said valve to pass through a tubing having a short radius bend therein.

3. A well tool for admitting fluids into the interior of a tubing including: articulatedbody means having a plurality of sections to permit movement through a tubing having bends therein; a concentric type valve in a first of said sections, said valve including a resilient valve element for admitting said fluids to said section for flow therethrough into said central flow passage, said section also having a check valve for preventing back flow of fluids from said tubing through said section; means pro viding a gas chamber in a second section of said body, said gas chamber being interconnected with said first section of said body means by a flexible conduit disposed annularly about the longitudinal flow passage between the body sections for conducting gas from the chamber to the valve element whereby a charge of gas within said chamber exerts a pressure behind said concentric valve to bias said valve element toward said inlet ports; and said second section including the means forming said gas chamber being laterally flexible to permit said second section to bend significantly to pass through tubing having bends of short radius therein.

4. A well tool for admitting fluids into the interior of a tubing including: an articulated body having a plurality of sections flexibly interconnected and provided with a fluid flow passage therethrough; a first section of said body being provided with first ports for admitting fluids into said section from around said section and second ports for passing said fluid admitted through said first ports into said central flow passage through said body, said first and second ports being interconnected by an annular space provided in said section; a concentric resilient valve element secured in said annular space in said first section for controlling fluid flow through said first ports into said section; a second of said sections including an annular laterally flexible gas chamber adapted to be percharged to a predetermined pressure and sealed; and laterally bendable annular conduit means between said first and second sections interconnecting said gas chamber and said annular space behind said concentric valve element for conducting pressure gas within the chamber to the valve element for exposing the back side of said valve element to the pressure of gas within said chamber for biasing said valve element toward said inlet ports in said first section; said annular laterally flexible gas chamber and said annular bendable conduit means providing for sgnificant bending of said body to permit said body to pass through a tubing having a bend of short radius therein.

5. A well tool for admitting fluids into the interior of a tubing including: an articulated body comprising a plurality of flexibly interconnected sections and provided With a longitudinally extending fluid flow passage therethrough; a first of said sections being provided with first ports for admitting fluids into said section from around said section and with second ports for discharging fluid admitted through said first ports into said central flow passage through said body, said first and second ports being spaced apart from each other and interconnected by an annular flow passage provided through said first section; a concentric resilient valve element secured within said annular flow passage in said first section and laterally movable for covering and uncovering said first ports; a second laterally flexible section of said body connected to said first section; laterally flexible annular conduit means in said second section providing a laterally flexible and bendable annular gas chamber adapted to be precharged to a predetermined pressure level and sealed; and passage means provided by said first and second sections communicating with said annular conduit means for interconnecting said gas chamber with the back side of said concentric valve element for exposing the back side of said valve element to the gas sealed within said chamber for biasing said valve element toward said inlet ports in said first section; said laterally flexible and bendable gas chamber providing for significant bending of said body to permit said body to pass through a tubing having a bend of short radius therein.

6. A well tool for admitting fluids into the interior of a tubing including: an articulated body comprising a plurality of flexibly interconnected sections and provided with a longitudinal flow passage extending therethrough; a first of said sections having port and passageway means for admitting fluid through said section into said longitudinal flow passage and a concentric valve element for controlling fluid flow through said port and passageway means; a second of said sections connected to said first section being laterally flexible; a helically wound tube secured concentrically within said second section; said first section being provided with passage means connected into the lower end of said tube in said second section for exposing said concentric valve element on the back side thereof to gas under pressure in said tube for biasing said valve element outwardly toward said port means in said first section; and means provided by said second section for charging said tube with gas and sealing said tube.

7. A Well tool for admitting fluids into the interior of tubing comprising: a tubular shaped mandrel having a central fluid flow passage therethrough; a sleeve secured around said mandrel and spaced apart therefrom forming a concentric annular space between said mandrel and said sleeve; said sleeve being provided with inlet ports into said annular space and said mandrel being provided with outlet ports connecting said annular space with said central fluid flow passage, said inlet ports and said outlet ports being spaced apart longitudinally; a concentric laterally flexible valve element secured in said annular space between said mandrel and said sleeve for opening and closing said inlet ports in said sleeve; a flexible tubular housing connected to one end of said mandrel; a helically wound tube secured at one end to said mandrel and concentrically positioned within said tubular member; said mandrel being provided with a fluid flow passage connected into said tube and extending into said annular space behind said concentric valve element for exposing the back side of said concentric valve element to the pressure of gas Within said tube; a head member secured to the other end of said tubular member for connecting said well tool to means for supporting said tool in a tubing; and said head member being provided with passage means connected into said tube in said tubular member whereby said tube may be charged with a gas and sealed.

8. A well tool for admitting gas into the interior of a tubing comprising: a tubular mandrel having a longitudinal fluid flow passage therethrough; a sleeve positioned around said mandrel and spaced apart therefrom to form an annular space around said mandrel; said sleeve being provided with inlet ports for admitting fluid into said annular space and said mandrel being provided with outlet ports for discharging fluids from said annular space into said central flow passage in said mandrel, said ports in said sleeve and said ports in said mandrel being longitudinally spaced apart from each other; a resilient concentric valve element secured in said annular space, said valve element being laterally flexible to open and close said inlet ports through said sleeve; said mandrel being provided with a fluid flow passage extending from one end thereof into said annular space behind said concentric valve element whereby a gas under pressure in said flow passage may exert a force against the back side of said valve element to bias said valve element toward said inlet ports of said sleeve; a flexible tubular housing secured at the lower end thereof to the upper end of said mandrel; a helically wound hollow tube secured at the lower end thereof to the upper end of said mandrel, said tube being connected into said fluid flow passage in said mandrel whereby gas in said tube may pass through said flow passage to exert a pressure behind said concentric valve element, said tube being concentrically positioned within said resilient tubular member; a head member secured to the upper end of said tubular housing and said helically wound tube for supporting said tool in a tubing, said head member being provided with a fluid flow passage extending through the wall thereof into communication with the upper end of said helically wound tube to permit said tube to be charged with gas; and means for sealing said flow passage in said head member subsequent to injection of gas into said helical tube.

9. A gas lift valve for admitting fluids into the interior of a Well tubing comprising in combination: an articulated body comprising a plurality of flexibly interconnected tubular sections each provided with a longitudinally extending flow passage to permit fluid flow through said body; a first of said sections comprising a gas actuated concentric valve for selectively admitting lift gas into the flow passage through said body; a second of said sections being laterally flexible and including a resilient tubular housing secured at one end to the first of said sections; a spirally wound tube concentrically positioned within said tubular housing and connected at one end to said concentric valve in the first of said sections; a third of said sections comprising a head member connected to the other ends of said tubular housing and said spirally wound tube; and said head member being provided with passage and closure means to permit said spirally wound tube to be filled with gas and said gas sealed in said tube for actuating said concentric valve and biasing said valve toward lift gas inlet ports in said first section.

10. A gas lift valve for admitting fluids into the tubing of a well including: a tubular mandrel having a longitudinal flow passage extending therethrough and provided with a concentric valve for admitting fluids through said mandrel into said flow passage in response to fluid pressure around said mandrel, said concentric valve being operable by gas pressure independent of the pressure in said flow passage through said mandrel; a flexible tubular housing secured at the lower end thereof in fluid tight relationship around the upper end of said mandrel; a spirally wound hollow tube connected at the lower end thereof to the upper end of said mandrel and concentrically positioned within said tubular housing, the lower end of said tube being in fluid communication with the back side of said concentric valve whereby gas pressure within said tube biases said concentric valve outwardly to control flow of lift gas into said mandrel, said tube and said tubular housing cooperating to form a laterally flexible section of said gas lift valve; and a head member secured to the upper end of said tubular housing and said spirally wound tube for connecting said lift valve to means for supporting said valve in said tubing, said head member being provided with fluid flow passage means connected into the upper end of said spirally Wound tube for injecting gas into said tube and with means for closing said passageway for sealing said gas within said spirally wound tube.

11. A gas lift valve for admitting lift gas into a tubing in a well including: a bottom sub; an annular packing assembly secured around said bottom sub; a flexible tubular housing secured at the lower end thereof to the upper end of said bottom sub; a tubular shaped concentric valve section secured at the lower end thereof to the upper end of said flexible housing, said concentric valve section comprising a tubular mandrel supporting a concentric gas actuated valve for admitting lift gas into said mandrel; and a laterally flexible dome section secured at the lower end thereof to the upper end of said mandrel, said dome section including a flexible tubular housing, a spirally wound hollow tube concentrically positioned within said housing, said tube being interconnected with said concentric valve whereby the pressure of gas within said tube biases said concentric valve toward a closed position; and a head member secured to the upper end of said last mentioned tubular housing gas lift valve within said tubing, said head member including passage means for injecting gas into said tube and means for closing said passage means to seal said gas in said tube.

12. A gas lift valve comprising in combination: a bottom sub; a flexible tubular connector secured to the upper end of said bottom sub; a tubular shaped concentric gas actuated admission valve secured at the lower end thereof to the upper end of said flexible connector; a laterally flexible tubular section secured at the lower end thereof to the upper end of said concentric valve, said tubular section including a significantly bendable annular flexible dome-gas chamber adapted to be filled with gas to a predetermined pressure for actuating said concentric valve, said dome gas chamber being interconnected with said concentric valve and having a longitudinal flow passage centrally extending therethrough; and a tubular head member connected to the upper end of said laterally flexible section, said head member including a fluid passage interconnected with said dome-gas chamber for injecting gas into said chamber and sealing said gas in said chamber; said annular flexible dome-gas chamber permitting said gas lift valve to bend significantaly to pass through a well tubing having a short radius bend therein.

13. A gas lift valve in accordance with claim 12 Wherein said dome-gas chamber comprises a spirally wound tube concentrically positioned within the laterally flexible tubular section of said valve.

14. A gas lift valve including: an articulated flexibly interconnected tubular shaped body having a longitudinal fluid flow passage extending therethrough; a first section of said body comprising a lower sub; a second section of said body comprising an annular flexible gas actuated for supporting said admission valve for controlling the flow of lift gas into said body; a third section of said body comprising an annular laterally flexible significantaly bendable concentric dome-gas chamber interconnected with said concentric valve for sorting gas for biasing said valve toward a closed position and having a flow passage longitudinally therethrough communicating with the longitudinal flow passage of the other sections; and a fourth section of said body comprising a head member connected to said laterally flexible section; said flexible dome-gas chamber third section providing for significant bending of said body of said valve to permit said valve to pass through well tubing having a short radius bend therein.

15. A gas lift valve for admitting lift gas into a well tubing comprising in combination: a tubular shaped head member having a longitudinal bore extending therethrough, said head member having a lateral opening into the wall thereof and a longitudinal flow passage interconnected with said lateral opening and extending within said wall through the lower end of said head member, said head member being further provided around the external surface of the lower portion thereof with a plurality of tooth-like ridges; means engageable with said lateral opening in said head member for sealing said opening; a tubular shaped flexible housing engaged at the upper end thereof around the lower portion of said head member; a deformable annular retainer engaged around the upper end of said tubular housing over said ridges on said mandrel to secure said housing on the lower portion of said head member; a spirally wound hollow tube concentrically positioned within said tubular housing, the upper end of said tube being connected into the passageway in the wall of said head member whereby gas injected through said passageway will flow into said tube, said tube serving as a storage chamber for dome gas and cooperating with said tubular housing to form a laterally resilient conduit through which well fluids may flow; a tubular shaped mandrel engaged at the upper end thereof with the lower end of said tubular housing, said mandrel being provided around the upper portion thereof with tooth-like ridges; a deformable annular retainer engaged around the lower portion of said tubular housing over said tooth-like ridges on said mandrel to secure said housing to said mandrel; said mandrel being provided with a portion of reduced external diameter along a portion of the length thereof and with a longitudinal flow passage extending from the upper end of said mandrel within the wall thereof and opening into said portion of reduced diameter of said mandrel, the lower end of said spiral tube being connected into said longitudinal flow passage in the wall of said mandrel whereby dome gas in said spiral tube is conducted within the wall of said man-drel to the said portion of reduced diameter; an annular shaped concentric, laterally resilient, valve element positioned around said mandrel along the portion of reduced diameter over the opening of the longitudinal flow passage from said spiral tube whereby gas present in said tube will exert a pressure behind said valve element to bias said element outwardly from said mandrel; an annular sleeve engaged around said mandrel and spaced apart therefrom to form an annular chamber around said mandrel encompassing saidvalve element, said sleeve being provided with inlet ports, said ports being covered and uncovered by said valve element, said valve element being normally biased by said dome gas toward said ports; said mandrel being provided with a plurality of ports extending through the wall thereof from said annular chamber into the central flow passage through said mandrel for admitting lift gas from said annular chamber into said mandrel; an annular, laterally flexible, check valve secured around said mandrel within said annular chamber between said ports in said mandrel and said concentric valve element to prevent the backflow of well fluids from within said mandrel toward said inlet ports; said sleeve being further provided with an internal portion of reduced diameter located around the lower portion of said concentric valve and the upper portion of said check valve, said portion being broached to form a plurality of longitudinal flow passages to permit flow of lift gas along the length of said annular chamber between said inlet ports and said ports in said mandrel; the lower end of said mandrel being provided with a plurality of external annular tooth-like ridges; a flexible tubular connector engaged at the upper end around the lower end of said mandrel over said toothlike ridges; an annular deformable retainer secured around the upper end of said connector to secure said connector to said mandrel over said tooth-like ridges; a tubular shaped bottom sub having an upper external portion provided with annular tooth-like ridges; the lower end of said tubular connector being engaged on the upper end of said bottom sub over said tooth-like ridges; an annular deformable retainer engaged around the lower end of said tubular connector over said tooth-like ridges on said bottom sub to secure said connector to said bottom sub; said tubular connector providing a laterally flexible connection between said mandrel and said bottom sub; and an annular packing assembly engaged around the external surface of said bottom sub.

References Cited UNITED STATES PATENTS 3,052,302 9/1962 Lagucki 106-153 3,075,475 1/1963 Otis 137-155 3,223,109 12/1965 Cummings 103232 X ALAN COHAN, Primary Examiner. 

